Process for treating fibers and the products produced



Patented Nov. 25, 1941 PROCESS FOR. TREATING FIBERS AND THE PRODUCTS PRODUCED Roger Wallach, Briarclifl Manor, N. Y., assignor to Sylvania Industrial Corporation, Fredericksburg, Va., a corporation of Virginia No Drawing. Application October 1, 1938, Serial Claims.

The invention relates in general to a treatment of cellulose fibers and in particular to a process for the production of textile fibers. to the fibers so produced, and to fabrics made therewith, and includes correlated improvements designed to enhance the quality, structure and properties of such fibers and fabrics whereby to extend their use in the textile and cordage arts.

7 There are a large number of fibers which have not heretofore been used in the textile arts, or which have been little used therein because they are normally smooth-surfaced and/or relatively straight and cannot be readily felted, carded, combed, spun and the like, to convert them into textiles. Such fibers exhibit. little or no felting characteristics because they tend to lie fiat.

against each other and have no substantial curl or crinkle.- The' yarns and fabrics made from such fiber are deficient in resistance to untwisting and loss of fibers; and show a fiat handle and a lack of the warmth and springines's which are characteristic of textiles made from wool and wool-like fibers. One of the objects of this invention is to render such cellulose fibers capable of being more readily felted, carded, combed, spun or otherwise worked up into textiles; to enable such fiber not heretofore utilized in the textile arts to be used more widely therein.

According to this invention, non-uniformity of the physical fiber structure involving roughness and irregularity of the fiber surface, and a substantial curl, that is a wooliike character, is prr iuced or enhanced by converting cellulose of the fibers into a compound of a chemical composition dissimilar to that of the starting material In-Great Britain October 2, 1937 but having a rough, irregular surface, and a substantial curl, which imparts to the fibers a woollike character. Accordingly, the product of the present invention is adapted for use in many structures of the textile and cordage arts for which the cellulose fibers heretofore known are not adapted, or not as well adapted.

Heretofore the chemical treatment of cellulose, whether in fibrous form or not, has had for its object the making of a product which may be dissolved in a solvent and then formed into'filamerits; Thus, it was customary to start with a raw material which was finely comminuted such aswood pulp, sulphite cellulose or cotton linters, all of which comprise fibers-not long enough to be used in the textile and cordage arts. Moreover, to insure a uniform chemical treatment and a uniformly soluble product,it was customary, heretofore, to comminute the cellulose before or during reaction as by shredding. In contrast thereto, in thepresent invention cellulose is treated in the form of fibers having initially a length cawhile maintaining or substantially maintaining normally smooth-surfaced and/or relatively straight cellulosic fibers by superficially, partially or completely converting the cellulose of the fibers into a compound of dissimilar chemical composition.

Thus the product of the present invention is characterized by having the macroscopic fibrous form. of the raw fibrous material from which it was prepared and having a textile making length,

pable of being utilized in the textile and cordage arts, while avoiding any shredding or other com-- minuting of the'fibers before, during or after reaction so as to prevent breaking of the fibers be-' low a textile-making length and the'macroscopic form of the fibers is substantially preserved.

Thus the conversion of the cellulose of the- Preferably, the conversion isv carried "out on fibers which are in a swollen condition as a result of treatment with a suitable swelling agent. Since the conversion treatment usually shrinks the fibers, the wool-like characteristic is enhanced by shrinking the swollen fiber. The swelling of the fiber is carried out under such conditions of temperature and concentration of swelling agent that the fibers are prevented from sticking together.

By the process according to this invention it is thus possible not only to retain the macroscopic fibrous form of, the. raw material, but also to ob- 'tain the product in the form of fibers capable of being separated readily one from another and which have novel wool-like characteristics, all

of which make the product of the present invention spinnable and adapted for-wider use in the textile and cordage arts.

The invention accordingly comprises the several steps and relation of one or more of such steps with respect to each of the others, and the article possessing the features, properties, and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

In the present invention the expression fiber" is intended to include all continuous filaments, whether artificial or naturally occurring, also staple fibers or schappei obtained by cutting continuous artificial filaments or natural fibers intofibers of textile-making lengths, and all naturally occurring vegetable fibers of textile-making length.

vThe expression cellulose as used herein is intended to include both cellulose in its naturally occurring state as well as cellulose hydrate and cellulose derivatives of all kinds.

The expression conversion as used herein includes all chemical changes by which cellulose of thefiber may be transformed into a cellulose compound of composition dissimilar to that of the starting material.

Among the naturally occurring fibers for which the present invention is especially adapted are all those'normally smooth-surfaced and/ or relatively straight vegetable fibers derived from plants, such as sisal, hemp, jute, fiax, palm.

- ester-ethers, mixed esters, mixed ethers, and cellulose compounds formed by condensing or polymerizing cellulose with itself or with another substance, also cellulos hydrate or regenerated cellulose obtained from viscose or solutions of cellulose in organic or inorganic solvents or cuprammonium cellulose.

The vegetable. fibers may be subjected to any suitable treatments for the removal of noncellulosic constituents which might interfere with the swelling and/or conversion reactions and which might render the fibers incapableof hydroxide, tetra-alkyl ammonium hydroxides and organic bases, such as amines; alkaline salts,

, ployed suitable inorganic or organic agents having regard to the nature of the particular cellulose derivative, for example, cellulose esters may be swollen with organic solvents such as acetone, ethyl acetate, butyl acetate, methylene chloride and the like, with or without non-solvent diluents, or with swelling agents which are nonsolvents, such as ethyl alcohol, di-ethylene glycol, lactic acid and the like. The swollen fibers of any kind may be carded to loosen them up before they are converted.

For converting the cellulosic material of the fiber, the particular methods selected will depend, inter alia, upon the nature of the cellulosic fiber, that is, whether it is cellulose, cellulose hydrate or acellulose derivative. If it is a naturally occurring cellulosic fiber, the treatment will depend, in particular, upon whether or not the fiber has been purified, oxidized, bleached; or otherwise modified before treatment by the present process. The chemical conversion treatments-are well known to those skilled in the art-and such treatments. per se form no being readily separated'by carding, combing and the like. For example, the resins, pectins, lignins, waxes, etc. may be removed from the naturaloccurring cellulose fibers in a known manner, prior to the conversion of such materials. Prefembly, with the straight vegetable fibers, suchas hemp. jute, flax, etc, the fibers are heated with dilute alkali to remove the non-cellulosic constituents and/or bleached in a, known manner before conversion.

It .is to be understood that no claim is made -to swellingJor mercerizing 'fibers per se when not used in conjunction with a chemical conversion of the cellulose of the fiber as herein part of the present invention when carried out on fibers of .less than textile-making length and/or when the fibers are broken during treatment below such lengths.

By way of illustrating, but not by way of lim- I iting the'invention, there may be given the following examples of methods of converting naturally occurring cellulosic vegetable fibers or cellulose hydrate fibers of all kinds:

(1) Methods involving substitution of the hydroxyl-radical in the cellulose by inorganic or organic substituent, for example by converting the cellulose in fiber form superficially, partially,

or completely into a cellulose derivative, such for example, asester, ether, mixed ester, mixed ether, mixed ester-ether, xanthate, thiourethane, xanthated ether, etherified xanthate, and the like; or

(2) By polymerizing the cellulose of the fiber, for example by the use of irradiation, heat, oxidation and the like, such polymerizations involving the hydroxyl radicals and/or the ketone radical in the cellulose; or

(3).By condensing the cellulose in fiber form with another substance, such for example, as an inorganic or organic compound such as phenolic compounds, aldehydes, polybasic acids, polyacid bases, quaternary alkyl ammonium hydroxides:

nitrogen-containing organic compounds, such as amines, urea, and in particular. the heterocyclic nitrogen compounds suchas pyrrole, pyridine, piperidine and their derivatives, also quaternary pyridinium compounds, inparticular halogen alkyl ethers of such pyridinium compounds; For example, cellulose fibers may be treated with an aqueous solution of a quaternary pyridinium salt such as octadecyl-oxymethyl pyridinium chloride and heated to above the decomposition temperature (about C.) whereupon the cellulose condenses vwith one of the decomposition products.

Such condensation being carried out by the use of suitable agents, heat and/or in the presence chemical nature but of lower or higher extent of substitution, or

(3) Into cellulose hydrate.

All the above methods may be generally classified for convenience as -uprising:

(a) the addition of substituents, or

(b) the loss of substituents, or

(c) the conversion of one type of substituent into another type.

- As in the case of the naturally occurring vegetablefibers or cellulose hydrate fibers, the filaments formed of cellulose derivative may be treated to polymerize the cellulose derivative or to condense the cellulose derivative with another substance. For example, an unsaturated cellulose ether, such as a crotyl cellulose in fibrous form may be polymerized by exposure to heat and/or light.

Thus according to the present invention, a vegetable material in the form of separable fibers is converted to an alkali-soluble cellulose ether in fibrous form by swelling the vegetable fibers with an alkali and the swollen fibers etherified with a suitable etherifying agent in an alkaline medium at a temperature and a concentration of alkali such that the fibers do not stick together and thereafter the alkali is removed and the product obtained in the form of separable fibers. When converting cellulose to a celluloseether there may be employed for the alkali an inorganic or organic base such, for example, as sodium hydroxide, potassium hydroxide, dimethylamine, quaternary ammonium .hydroxides, in particular a tetra-benzyl ammonium hydroxide. During'the alkalizing treatment, the concentration of the alkali may be from 10% to 25% by weight. During etherification the ratio by .weight of dry cellulose on the basis of CsHroOs to solid alkali calculated as NaOH preferably should not exceed 1:02, the water present during reaction being such that the concentration of the alkali solution is not above 25%.

For the etherifying agent, there may be employed any suitable alkyl ester of an inorganic acid such, for example, as ethyl chloride, diethyl oxide, propylene oxide; also glycides and the like.. It is understood that when a halohydrin The conditions under which the etherifying reaction takes place should be carefully controlled. In general this reaction should be car- .ried out while the cellulose is in an alkaline medium. The temperature of the etherifying treatment may be varied having regard for the nature of the cellulose and the nature of the particular etherifying agent employed. When cotton is employed as the raw material and ethylene oxide as the etherifying agent, a suitable temperature for reaction is from 15 C. to 30 C. The reaction is preferably carried out in a closed vessel. After removing the unused etherifying agent, as by centrifuging or by evacuation of the agent, the product is washed and then again centrifuged, and allowed to dry or dried at elevated temperature preferably by blowing a blast of warm air upward through the mass of wool-like fibers.

When the conversion. process is one which tends to give a fibrous product which is soluble in water or aqueous solutions, the sticking together of the fibers during treatment and the solubility of the converted cellulose may be prevented or retarded by carrying out the swelling and/or conversion in the presence of a large quantity of a water-soluble inert salt. For example, in converting cellulose to a cellulose ether there may be added to the alkali or to the reaction mixture from 10% to 20% by weight of a salt such as sodium or potassium chloride, sodium or potassium sulphate, sodium or potassium nitrate, and the like.

It is to be understood that, generally, with nonuniform, natural or artificial cellulose 'fibers the swelling and/or conversion may be superficial, partial or complete conversion of the cellulose, that is, the conversion may occur in a superficial surface area or the conversion may extend throughout the cross-section of the fiber and throughout the length.

With artificial fibers of uniform composition such as those made of cellulose hydrate or of a cellulose derivative the swelling and/or the con- 1 version may be superficial, partial or complete length and in such, cross-sectional areas the conversion may be partial or complete.

To effect the swelling and/or conversion of the cellulose non-uniformly or irregularly one may: (1) Apply the swelling agents and/or the conversion reagents over the entire surface of naturally-occurring vegetable fibers which have not been freed completely from non-cellulosic constituents and depend upon the non-reactivity thereof to give a wool-like effect to the treated fiber. (2) Apply the swelling agents and/or conversion reagents non-uniformly or irreguis employed, sufiicient alkali should be present a larly as by spraying the fibers with the swelling agents and/or conversion reagents. (3) Apply the swelling agents and/or conversion reagents uniformly over the surface of the fibers and thereafter irregularly modify the activity of the swelling agents and/or conversion reagents.

By way of further example, a cellulose triacetate fiber may be de-esterified in non-uniform or irregular areas into a cellulose diacetate; similarly, a cellulose ether fiber is irregularly esterified to produce a mixed cellulose ether ester; a fiber formed of a cellulose ether of low alkylation is irregularly etherified to'for'm an ether of higher alkylation. V

It will be apparent that other methods and means of effecting a conversion of the cellulose to a compound of dissimilar chemical constitution will suggest themselves to those skilled in the art following the principles herein set forth and without transcending the scope of the invention.

It is to be understood that the treatment with l the swelling agents and/or with the chemical cation or in conjunction with various fiber treatments either manufacturing or finishing, such, for example, as before, during and/or after carding, roving, dyeing, bleaching, sizing, weighting,

delustering, mothproofing, waterproofing, fire-" proofing and the like.

The cellulose fiber may be mixed with an inert fibrous material before being swollen and/or converted to wool-like fibers. For example, one may employ a mixture of any vegetable fiber and a mineral fiber such as asbestos or glass or a mixture of a vegetable fiber and synthetic inert fibers, such as resin or rubber.

In the now preferred embodiment, the cellulose fibers to be treated may be out to suitable staple lengths, if necessary, and after'swelling,

and pressing the-swollen fibers as dry as possible, 1

subsequently carding the fibers before conversion to produce a card sliver or a roving sliver, by which the fibers are arranged in substantially parallel relationship. The conversion is then carried out preferably continuously on the fibers in the sliver without mechanically disturbing them whereupon there is obtained a fibrous product which can be more readily separated by carding, combing and the like. Thereafter the converted wool-like fibers are purified, dried and fabricated by known means, i. e., carded, spun, woven into textiles.

The new and novel fibers produced by the present invention enables one to obtain new textiles having technically valuable propertieswhich had not been obtained heretofore by the use of known natural or artificial fibers. The effects obtainable in textiles can be varied widely according to the raw fiber treated and to the particular methods of swelling and/or converting to which they are subjected in the present invention. Among other uses, the fibers of the invention may be employed alone or in admixture with each other or with untreated artificial or natural fibers in the fabrication of various types of textiles such, for example, as slivers, rovings, yarns, threads and cords of all kinds, whether single or plied, fabrics of all kinds as made by weaving, knitting, netting, lacing, braiding, and other fabrication processes, and felts of moulding fibers with binding agents and having sufiicient structure to enable them to be used in the textile and allied arts. The converted cellulosic fibers may be mixed with naturally curly fibers such as wool and the mixture felted, carded, combed, spun and the like to give novel textiles. In particular, the fibers of the invention are adapted to take the place of part or of all of the natural wool in woolen textiles of all kinds.

By the present invention there is obtained a new and novel series of fibers having technically valuable properties which are not found in known natural or artificial fibers. In fact, the woollike fibers of the invention retain many of the valuable properties of the fibers from which they were produced such as fibrous form, tenacity, and

the like and, in addition, acquire some oi the properties of the cellulose derivatives, such as partial or complete solubility in solvents, heat plasticity, extensibility, and the like. The effects obtainabl in the treated fibers can be varied widely according to the nature of the raw fiber 4 remarkable property of having a greater strength while wet than while dry in common with the unconverted natural fibers, but in marked contrast to filaments of cellulose derivatives made artificially by prior processes which filaments always show a decreased tenacity when wet. Further, the fibers exhibit, by reason of their curled, crinkled and irregular fiber structure, a wool-like behaviour in felting, carding, combing and spinning, so that they may be fabricated into higher grade textiles more readily than the untreated smooth straight fibers.

The yarns, threads, cords and the like made from the fibers of the invention are characterized by a higher elasticity, tenacity. extensibility, and a decreased tendency to untwist or to lose short fibers, and they shrink less on wetting and drying than similar articles made of the 'un- 'treated fibers. The felts, fabrics and other texthey are again dried. In fact, the curliness of the fibers tends to be increased by suchtreatments. The present invention permits the use in textiles of fibers not heretofore used therein and a wider use of fibers little used. Shorter fibers may be used in," textiles while obtaining products as strong as those formerly obtained with untreated but longer fibers and the treated fibers can be formed into finer sizes of yarns than the untreated fibers. With the present woollike fibers, yarns can be formed with lower degrees of twist than is possible with untreated fibers of the same length.

Since certain changes in carrying out the above process, and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent 1s:

1. As an article of manufacture, a wool-like cellulose fiber of textile-making length obtained by the process defined in claim 6 and characterized by the individual fibers having a substantial crinkle and irregularity of chemical and physical structure and having the property of swelling non-uniformly in the presence of swelling agents.

2. As an article of manufacture, a wool-like cellulose fiber of textile-making length containing a cellulose ether, said fiber being obtained by the process described in claim 10 and characterized by the individual fibers having a substantial crinkle and irregularity of chemical and physical structure and the property of swelling non-uniformly in the presence of swelling agents.

3. As an article of manufacture, a textile containing wool-like cellulose fibers obtained by the process defined in claim 6 and characterized by the individual fibers having a substantial crinkle and irregularity of chemical and physical structure and the property of swelling non-uniformly in the presence of swelling agents.

4. As an article of manufacture a yarn containing wool-like cellulose fibers having a nonuniform cellulosic composition, said fibers being obtained by the process described in claim 6 and characterized by the individual fibers having a substantial crinkle and irregularity of chemical and physical structure and the property of swelling non-uniformly in the presence of swelling agents.

5. As an article of manufacture a fabric containing wool-like cellulose fibers including a product of a non-uniform conversion of cellulose of natural vegetable fibers into a cellulose compound having a different chemical composition from that of the natural cellulose fiber, said wool-like fibers being obtained by the process described in claim 6 and characterized by the individual fibers having a substantial crinkle and irregularity of chemical and physical structure and the property of swelling non-uniformly in the presence of swelling agents.

6. A process for the production of a cellulosic fore treatment, with maintenance of the macroscopic fibrous form and the production of a permanent wool-like crinkle and irregularity of chemical and physical fiber structure.

7. A process for the production of a cellulosic textile fiber having a wool-like character which comprises treating cellulose fiber with a swelling agent and then applying a conversion agent to the swollen fiber while in loose condition in an irregular manner at irregularly spaced intervals throughout the length of individual fibers, said application effecting a chemical conversion of fiber substance to a compound having a different chemical composition from that of the fiber before treatment, with'maintenance of the macroscopic fibrous form and the production of a permanent wool-like crinkle and irregularity of chemical and physical fiber structure.

8. A process for the production of a cellulosic textile fiber having a wool-like character which comprises applying a conversion agent to a cellulose derivative fiber while in loose condition in an irregular manner at irregularly spaced intervals throughout the length of individual fibers, said application effecting a chemical conversion of fiber substance to a compound having a different chemical composition from that of the fiber before treatment, with maintenance of the macroscopic fibrous form and the production of a permanent wool-like crinkle and irregularity of chemical and physical fiber structure.

9. A process for the production of a cellulosic textile fiber having a wool-like character which comprises applying a conversion agent to a cellulose derivative fiber while in loose condition in an irregular manner at irregularly spaced in-- tervals throughout the length of individual fibers, said application effecting chemical conversion of the cellulose derivative into another derivative having a difierent chemical composition from that before treatment, with maintenance of the macroscopic fibrous form and the production of a permanent wool-like crinkle and irregularity of chemical and physical fiber structure.

10. A process for the production of a cellulosic textile fiber having a wool-like character which comprises treating cellulose fiber while in loose condition with a swelling agent at a temperatureat which the fibers do not stick together, then applying an etherifying agent in the presence of an alkali to the thus swollen fibers in loose condition in an irregular manner at irregularly spaced intervals throughout the length of individual'fibers, said application efiecting a conversion of fiber substance into a cellulose ether, with maintenance of the macroscopic fibrous form and the production of a permanent woollike crinkle and irregularity of chemical and physical fiber structure, said etherification taking place at a concentration of alkali and a temperature which obviates a sticking together of fibers.

ROGER WALLACH. 

